Approach Considerations
When assessing sleeplessness, a sleep log is often used. Although not technically a laboratory test, this diary allows identification of sleep-wake cycles in the patient's normal environment and permits subjective assessment of alertness over a 2-week time period. The Practice Parameters (2007) from the American Academy of Sleep Medicine recommend the use of sleep logs in the evaluation of the following sleep disorders [9] :
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Shift-work syndrome
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Jet lag
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Advanced sleep-phase syndrome (ASPS)
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Delayed sleep-phase syndrome (DSPS)
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Free-running disorder
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Irregular sleep-wake rhythm
Failure to diagnose other medical conditions associated with increased daytime sleepiness, such as obstructive sleep apnea (OSA), may carry significant consequences in terms of added morbidity and mortality. Another potential treatment pitfall is failure to assess a patient’s risk for motor vehicle accidents.
Implicit in the diagnosis of circadian rhythm disorder is a desire to conform to traditionally accepted sleep-wake patterns.
Imaging studies
Consider imaging studies if the patient is to be evaluated for neurodegenerative disease. Also consider imaging studies in patients with OSA to determine the etiology of obstruction.
Actigraphy
An actigraph is a small motion-sensing device worn on the nondominant wrist, generally for 1 week. It is based on the premise that wrist motion is decreased during sleep. This allows a very gross measurement of sleep-wake cycles over time.
Overnight polysomnography
This study is of value in identifying the patient with OSA, periodic limb movements of sleep (PLMS), or sleep-state misperception. It also is used in conjunction with the Multiple Sleep Latency Test (MSLT) to evaluate patients with narcolepsy. It is not routinely used in the diagnostic evaluation of patients with insomnia or in the diagnostic evaluation of patients with circadian rhythm disturbances.
Sleep Tests
Multiple Sleep Latency Test
The MSLT allows for objective measurement of sleepiness. Normal adult values range from 10-20 minutes, whereas sleep latencies of less than 5 minutes indicate abnormal sleepiness. MSLT is indicated when suspicion of narcolepsy is raised by the clinical history. Following a normal night's sleep documented by overnight polysomnography, specific abnormalities in MSLT (ie, 2 or more sleep-onset rapid eye movements [SOREMs]) support a diagnosis of narcolepsy.
Epworth Sleepiness Scale
The Epworth Sleepiness Scale (ESS) is based on a questionnaire that asks patients to rate their responses to 8 situations on a scale of 0-3, based on whether the situation was likely to be associated with dozing behavior. It was designed to give an indication of sleepiness and has been correlated with sleep apnea.
Morningness Eveningness Questionnaire
The evidence is insufficient to recommend the routine use of the Morningness Eveningness Questionnaire (MEQ) for the evaluation of circadian rhythm disturbances.
